Press Eraser 
, and then select an available eraser type.
SMART Notebook 10 for Mac Operating Systems
You can erase digital ink from the interactive screen using the eraser (on interactive whiteboards) or the Eraser pen tool button (on interactive pen displays). However, if you're erasing from a page of a .notebook file, you can also erase objects using the Eraser toolbar button.
NOTES
You're not able to erase some types of objects, including typed text, shapes, straight lines and arcs and imported graphics. To remove these types of objects, you must delete them.
You can remove all objects on a page by clearing the page.
Press Eraser , and then select an available eraser type.
TIP: If the available eraser types cover the digital ink you want to erase, press the X symbol to the right of the available eraser types.
Erase digital ink from the interactive screen.